So I can't answer the question directly in terms of giving a list of reasons but I do want to point out that there are a number of misconceptions in the view of Chinese history mentioned above.

First of, while the Zhou dynasty was a major state, in terms of size it was equal or smaller to empires that existed at the same time as it such as Assyria, Egypt or Persia and certainly smaller than many later dynasties. Moreover, at its height it was a relatively decentralised state with military power reliant on aristocratic lords and their domains. So while yes, the Zhou dynasty was an empire 200 years before Rome, it wasn't remarkable in size compared to a lot of its contemporaries and would not have been able to mobilize the same kind of resources as many later Chinese dynasties after a more direct rule and a bureaucracy were established.

China also fought (and lost) many significant external conflicts. The early Han dynasty was often beaten and forced to concede to demands by the Xiongnu nomads to the north. During the Jin dynasty the empire was invaded by northern peoples and northern China was ruled by several kingdoms of "barbarians" for a good long while. In the disastrous aftermath of the An Lushan rebellion the Tibetan empire sacked the imperial capital and conquered a lot of land. When the Tang finally collapsed there were plenty outside invasions again, and the Song dynasty that emerged from the conflict eventually also suffered setbacks at the hands of the Tanguts, Khitans and Jurchen (and of course, the Mongols, who you mentioned). And the Ming dynasty that got the fame of driving out the Mongols themselves also struggled with them, first with the Oirat Mongols and later with a new group of Mongols under Altan Khan. And then of course, they were themselves conquered by the Manchu who became the Qing dynasty. And that's not to mention the many conflicts within China itself like the Warring States period or the aforementioned An Lushan rebellion which certainly hindered any sort of imperial project.*

Finally technological inventions =/= imperial dominance. The compass and the printing press for example, while cool things to have, don't make it any easier to conquer Central Asia. Their use is in other fields. And something like gunpowder didn't take long to spread to other people, thus negating any advantage derived from that.

So, what stopped them from using their inventions and lack of conflicts from taking over the world is that their inventions didn't give them a giant advantage when fighting others and they had plenty of conflicts to deal with in reality.

*Of course that sort of sharp distinction of conflicts initiated by outsiders and by Chinese themselves isn't quite as clear cut in reality. Many of the "foreign" peoples who invaded had close ties with the Chinese and would soon adopt many aspects of their culture. Meanwhile a lot of the wars between Chinese weren't simple civil wars in a divided Chinese entity but wars between full-on autonomous states. This is very much an oversimplification for the sake of answering the question. I'll also add that you can probably find a lot more conflicts on China's southern border, I'm just not as familiar with that area.